Resistance wire



Patented Sept. 12, 1933 UNITED STATES PATENT OFFICE RESISTANCE WIRE NoDrawing. Application January 17, 1930 Serial No. 421,599

' 1 Claim.

This invention relates to an improvement in resistance wire for electriccurrent and more particularly to resistance wire for use under theconditions and for the purposes where heretofore, for

5 example, platinum only has been found to give satisfactory results;

As is well known in connection with various uses a resistance wire isrequired, or desirable, which will have high electrical resistance andat 0 the same time a small thermic coeflicient of its resistance, and inmany instances which will have high tensile strength and resistance tocorrosion in the air. Heretofore the conditions outlined have been metpartially by platinum and partially by constantan. Platinum has a highthermic coeflicient of resistance and apart from that its exceptionallyhigh cost is a serious disadvantage. Constantan has the disadvantage ofbeing rapidly corroded by the air.

Now it is the object of this invention to pro-' vide a resistance wirewhich will have desired high resistance; a small thermic coefficient ofits resistance; exceptionally high tensile strength; will be resistantto corrosion in the air; capable of being readily soldered withoutcorrosion to a support or terminal, which will be of relatively low costand may be easily drawn and which will be adaptable for varous uses,with increased efliciency, in place of platinum or constantan as, forexample, in Wheatstone bridges, and for similar purposes, and for thebridge wires in blasting caps, etc., etc.

In accordance with this invention I provide a resistance wire formedfrom an alloy of gold, which may be of any suitable purity and nickel insuitable proportions, the wire being drawn to a size, or cross sectionalarea, such that the resistance per unit of length will meet therequirements Lo of the particular use for which the wire is intended.

The resistance wire in accordance with this invention may desirablycomprise an alloy composed of gold within about the range 5%-99% andnickel within about the range 95%-1% suitably melted together or alloyedin accordance with the usual practice in alloying metals and drawn intowire of any suitable size to give the resistance required per unit oflength. While the re- ;o sistance wire embodying this invention may becomposed of an alloy of gold and nickel within the broad range given,the proportions of gold and nickel will more desirably be within thenarrower range of about 42%-75% gold and about $5 58%-25% nickel. Formany purposes the wire may desirably be composed of about 58.4% gold andabout 41.6% nickel.

As illustrative of, for example, resistance wire embodying thisinvention for use as bridge wire for blasting caps, the wire willdesirably comprise an alloy containing say about 58.4% of gold, and41.6% of nickel drawn to a size such that it will have a resistance ofsay about 360 ohms per yard. The proper length of wire is secured to theusual leg wires of an electric blasting cap by soldering, with anordinary soldering iron, using, for example, a solder desirablycontaining about 67% tin and about 33% lead and using as a solderingflux either ordinary rosin or an ordinary soldering solution, as anaqueous solution of zinc chloride, ammonium chloride and hydrochloricacid. Such bridge wire will not be corroded by the soldering flux, andwill efiiciently fire, the various compounds used for charging blastingcaps.

For the various uses to which the resistance wire, in accordance withthis invention and having the characteristics pointed out, may be put,the wire will be drawn to a size to provide resistance per unit oflength desired, as will be obvious, and will be secured in place in anysuitable manner.

It will be understood that the resistance wire in accordance with thisinvention may be comprised of gold, of various degrees of fineness, and,nickel in various proportions, it being understood that it is not theintention to limit this invention to the proportions of gold and nickel,or to the fineness of the gold indicated herein as desirable orpreferable. It will be further understood that while the use ofresistance wire embodying this invention has been illustrated more

